Moisture removal system

ABSTRACT

A moisture removal system comprises a plurality of coils each capable of operation as either a condenser or evaporator, and a switching mechanism to cycle the functionality of the coils. The system may cycle the functionality of the coils to alleviate frost development on any one coil and thus speed a moisture removal process.

BACKGROUND

The disclosed embodiments relate generally to dehumidification systems, and more particularly to systems directed at removing moisture from agricultural or other moisture-laden products.

It is often necessary or advantageous to lower the moisture content of certain products, including agricultural commodities. Corn, soybeans, wheat, oats, and even leafcutter bees are examples of products that require moisture removal for shipping, storing, and processing. The process of removing moisture from such commodities may be accomplished by closed-loop refrigeration methods. This involves forcing air over or through the subject product—i.e., the product from which moisture is to be removed—and then extracting moisture from the circulating air. The employed refrigeration systems typically include a heat pump, which comprises a condensing coil and an evaporator coil. Moisture from the circulating air adheres to the evaporator coil, thus lowering the relative humidity of the circulating air. After some time of operation, the moisture content of the subject product is reduced to a desired amount.

One problem with heat pump-based systems, however, is that the evaporator coil accumulates frost; and, at some point, the coil becomes so frosted that the evaporator coil no longer functions to remove moisture from the air. The typical solution to this frost issue is to cease operation of the heat pump in order to defrost the coil. This, of course, limits the effective operating time of the heat pump.

SUMMARY OF THE DISCLOSURE

Disclosed here is a moisture removal system with a heat pump that employs alternating cycles of operation, reversing functions of the condenser coil and the evaporator coil at certain intervals or when specified conditions are present. This allows the heat pump to continue operating while simultaneously thawing the frosted coil. In this way, the moisture removal process is sped up because there is no need to cease operation of the system to defrost a coil.

In accordance with some embodiments of the disclosed technology, a moisture removal system employs a dual evaporator. Air is forced through or over the subject product and circulated through a drying enclosure. Within the drying enclosure, the air travels over or through several coils, at least one of which is operated as a condenser and one an evaporator. Moist air enters the removal, or evaporator coil, which is operated at temperature below freezing. The moisture from the air adheres to the coil, which drops the relative humidity of the air. Then, when the evaporator coils is frosted, the system is cycled such that the functions of at least two coils are reversed: at least one coil that initially operated as a condenser changes to an evaporator, and at least one coil the initially operated as an evaporator changes to a condenser. The process continues until the subject product reaches desired moisture content.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of one embodiment of the disclosed moisture removal system.

FIG. 2 depicts one cycle of operation of an embodiment of a heat pump in the disclosed moisture removal system.

FIG. 3 depicts one cycle of operation of an embodiment of a heat pump in the disclosed moisture removal system.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the disclosed concepts. It will, however, be apparent to one of ordinary skill in the art that the disclosed concepts may be practiced without these specific details. Well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments.

FIG. 1 shows a moisture removal system 10, which comprises a product container 12 with an intake side 14 and an exhaust side 16. The subject product is placed in the product container 10. There is a drying enclosure 18 with an inlet side 20 and an outlet side 22. The drying enclosure 18 comprises a heat pump 24. The heat pump has a first coil 28 and a second coil 30. Also included are a first expansion valve 32 (which may also be referred to as a thermal expansion valve or TEV) and a switching means 34. The heat pump has a compressor 26, which is in fluid communication with the coils via a system of conduit, or conduit means 36. The conduit means 36 could be copper tubing, polypipe, galvanized piping, or an equivalent fluid conveyance means.

The moisture removal system 10 has one or more sections of duct for conveying air through the system. In a preferred embodiment, there is a first section of duct 38 that is connected between the exhaust side 16 of the product container 12 and the inlet side 20 of the drying enclosure 18. There is a second section of duct 40 which is connected between the outlet side 22 of the drying enclosure 18 and the intake side 14 of the product container 12. At least one blower 42, which, in FIG. 1, is shown in the first section of duct 38, circulates air 43 through the system. The blower 42 could be located in either the first section of duct 38 or the second section of duct 40. The blower 42 circulates air 43 through the moisture removal system 10, thus force air over or through the subject product within the product container 12 and through the drying enclosure 24. The moisture removal system 10 could employ a plurality of blowers 24, as may be required by specific designs and embodiments.

The heat pump 24 may be equipped with a third coil 44 and a second expansion valve 45. Additionally, it may be equipped with a four-way valve 46 and a plurality of flow control devices 48.

In one embodiment, in which the heat pump 24 comprises three coils, there is a first coil 28 having a condenser inlet 50, an evaporator inlet 52, and a valve outlet 54. There is also a second coil 30 having a first outlet 56, a second outlet 58, and a valve inlet 60. There is a third coil 44 having a condenser inlet 62, an evaporator inlet 64, and a valve outlet 66. In such an arrangement, the first coil 28 and the third coil 44 are each capable of operating as either a condenser or evaporator. The compressor 26 has a suction inlet 68 and a discharge outlet 70. The four-way valve 46 has a first coil inlet 72, a second coil outlet 74, a third coil inlet 76, and a compressor outlet 78. The first expansion valve 32 has an inlet 80 and an outlet 82, and the second expansion valve 45 has an inlet 84 and outlet 86.

In this embodiment, the heat pump 24 is operated in either of two cycles. FIG. 2 depicts a first cycle. In FIG. 2, the first coil 28 and the second coil 30 operate as a condenser, while the third coil 44 operates as an evaporator. During the first cycle, the compressor 26 provides refrigerant to the first coil 28 via a conduit means 36. The conduit means 36 is connected from the discharge outlet 70 of the compressor 26 to the condenser inlet 50 of the first coil 28. Within the conduit means is a flow controlling device 48 (FIG. 1). The flow controlling device could be either a solenoid or a check valve, or any other similar means of controlling the flow in a conduit or pipe.

The refrigerant leaves the first coil 28 at valve outlet 54 and moves to the second coil 30, which acts as a secondary condenser, via the four-way valve 46. The second coil outlet 74 of the four-way valve 46 is connected to the valve inlet 60 of the second coil 30 via conduit means 36. Next, the refrigerant moves from the second coil 30 to the third coil 44, which operates as an evaporator, via a second expansion valve 45. The second outlet 58 of the second coil 30 is connected to inlet 84 of the second expansion valve 45 via a conduit means 36. Within the conduit means 36 is a flow-controlling device 48 which, again, could be either a solenoid or a check valve, or any other similar means of controlling the flow in a conduit or pipe. The outlet 86 of the second expansion valve 45 is connected to the evaporator inlet 64 of the third coil 44 via a conduit means 36.

The refrigerant is then circulated back to the compressor 26 by way of the four-way valve 46 and the accumulator 88. The valve outlet 66 of the third coil 44 is connected to the third coil inlet 76 of the four-way valve 46. The compressor outlet 78 of the four-way valve 46 is connected to the valve inlet 90 of the accumulator 88 via conduit means 36; and the compressor outlet 92 of the accumulator 88 is connected to the suction inlet 68 of the compressor 26 via conduit means 36. The preferred embodiment includes an accumulator 88; however, those skilled in the art will recognize that a compressor with an internal or integral accumulator may also be used.

FIG. 3 depicts a second cycle of the heat pump 24. The compressor 26 is connected to the third coil 44, which acts as a condenser, as does the second coil 30. During the second cycle, the compressor 26 provides refrigerant to the third coil 44 via a conduit means 36. The conduit means 36 is connected from the discharge outlet 70 of the compressor 26 to the condenser inlet 62 of the third coil 44. Within the conduit means is a flow controlling device 48 (FIG. 1). The flow controlling device could be either a solenoid or a check valve, or any other similar means of controlling the flow in a conduit or pipe.

The refrigerant leaves the third coil 44 at valve outlet 66 and moves to the second coil 30, which acts as a secondary condenser, via the conduit means 36 and the four-way valve 46. The second coil outlet 74 of the four-way valve 46 is connected to the valve inlet 60 of the second coil 30 via conduit means 36. Next, the refrigerant moves from the second coil 30 to the first coil 28, which operates as an evaporator, via a first expansion valve 32. The first outlet 56 of the second coil 30 is connected to inlet 80 of the first expansion valve 32 via a conduit means 36. Within the conduit means 36 is a flow-controlling device 48, which, again, could be either a solenoid or a check valve, or any other similar means of controlling the flow in a conduit or pipe. The outlet 82 of the first expansion valve 32 is connected to the evaporator inlet 52 of the first coil 28 via a conduit means 36.

The refrigerant is then circulated back to the compressor 26 by way of the four-way valve 46, and the accumulator 88. The valve outlet 54 of the first coil 28 is connected to the first coil inlet 72 of the four-way valve 46. The compressor outlet 78 of the four-way valve 46 is connected to the valve inlet 90 of the accumulator 88 via conduit means 36; and the compressor outlet 92 of the accumulator 88 is connected to the suction inlet 68 of the compressor 26 via conduit means 36.

Referring again to FIG. 1, the switching means 34 operates to change the operation of the heat pump 24 between the first cycle and second cycle discussed above. The switching means 34 accomplishes this by adjusting the four-way valve 46 and opening and closing flow-controlling devices 48 such that the flow of refrigerant changes course and thus alternates the respective functions of the first coil 28 and the third coil 44. Those skilled in the art will recognize that some of the flow-controlling devices 48 will begin in a normally open state and some in a normally closed state. The switching means 34 thus changes the respective states of the flow-controlling devices 48.

In the preferred embodiment, the switching means comprises a timer that operates the flow-controlling devices to alternate the function of the first coil 28 and the third coil 44 in set increments. In the best mode presently known, the switching means comprises a timer set to fifteen-minute increments. The switching means could, however, comprise a temperature gauge and the cycling of the first coil 28 and the third coil 44 could be based on the temperature at a given point in the system. In one embodiment, the temperature gauge could reference refrigerant temperature at the outlet 82 of the first expansion valve 32 or the outlet 86 of the second expansion valve 45. (Whether to measure at the first expansion valve 32 or the second expansion valve 44 of course depends in which cycle the heat pump is operating.) Or, a switching means comprising a pressure gauge that could measure pressure at a given point in the system and switch the functionality of the first coil 28 and the third coil 44 when the pressure reaches a certain limit.

As the circulating air 43 travels through the coils, moisture adheres to the coil operating as an evaporator and the relative humidity of the circulating air 43 is reduced. This moisture removal occurs because the temperature of the refrigerant in the coil, and thus the coil itself, is below freezing. In one embodiment, the temperature of the system refrigerant is about −11 degrees Fahrenheit, as measured at outlet 82 or outlet 86, depending on the cycle of operation. But those skilled in the art will recognize that a range of temperatures will be suitable for moisture removal.

The disclosed technology may be operated using a method with the following. First, provide a moisture removal system 10, as described above. Then, circulate air through the system with the blower 42. Next, run the heat pump in a first cycle, as depicted in FIG. 2, with a switching means 34 configured for automatically switching the system 10 to operate in FIG. 3. When a predetermined condition is met—an expiration of time or a certain temperature or pressure measured—automatically switch operation of the system 10 to run the heat pump as depicted in FIG. 3. Finally, continue alternating between the first and second cycle until the subject product is at desired moisture content.

The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. The illustrative discussion above, however, is not intended to be exhaustive or to limit the disclosed concepts to any particular form. The embodiments were chosen and described in order to best explain the principles of the disclosed concepts in order to enable others skilled in the art. 

What is claimed is:
 1. A moisture removal system comprising: a product container for holding a subject product, said product container having an intake side and an exhaust side; a drying enclosure for removing moisture from circulating air, said enclosure having an inlet side and an outlet side and comprising a heat pump, which further comprises: a compressor; a first coil capable of operation as an evaporator or a condenser; a second coil capable of operation as an evaporator or a condenser; an expansion valve for coupling said first and second coils; and a switching means for changing the respective function of said first and second coil from condenser to evaporator or evaporator to condenser; wherein said compressor, first coil, second coil, and expansion valve are each in fluid communication with one another by way of conduit means; a first section of duct for conveying air from said product container to said drying enclosure, said first section of duct connected between said exhaust side of said product container and said inlet side of said drying enclosure; a second section of duct for conveying air from said drying enclosure to said product container, said second section of duct connected between said outlet side of said drying enclosure and said intake side of said product container; and at least blower mounted within one of said sections of duct for forcing air over said product; wherein said product container and said drying enclosure are in fluid communication with one another by way of said sections of duct.
 2. The moisture removal system of claim 1 which further comprises a third coil and an additional expansion valve, wherein said third coil is coupled to said second coil by said additional expansion valve, and each of said coils are in fluid communication with one another by way of conduit means.
 3. The moisture removal system of claim 2 which further comprises a four-way valve in fluid communication with said first, second, and third coils and said compressor.
 4. The moisture removal system of claim 1 which further comprises a plurality of flow-controlling devices each comprising at least one of: a solenoid or check valve.
 5. The moisture removal system of claim 1 wherein said switching means is a timer.
 6. The moisture removal system of claim 1 wherein said switching means is a pressure gauge.
 7. The moisture removal system of claim 1 wherein said switching means is a temperature gauge.
 8. A moisture removal system comprising: a product container for holding a subject product, said product container having an intake side and an exhaust side; a drying enclosure for removing moisture from circulating air, said enclosure having an inlet side and an outlet side and comprising a heat pump, which further comprises: a first coil having a condenser inlet, an evaporator inlet, and a valve outlet; a second coil having a first outlet, a second outlet, and a valve inlet; a third coil having a condenser inlet, an evaporator inlet, and a valve outlet; a compressor with a suction inlet and a discharge outlet; a four-way valve having a first coil inlet, a second coil outlet, a third coil inlet, and an compressor outlet; a first expansion valve having an inlet and an outlet; a second expansion valve having an inlet and an outlet; a plurality of flow-controlling devices each comprising at least one of: a solenoid or check valve; and a switching means operable to change the state of said flow-controlling devices for changing the fluid operation of said heat pump to change the respective function of said first and third coil from condenser to evaporator or evaporator to condenser; wherein said suction inlet of said compressor is in fluid communication with said compressor outlet of said four-way valve compressor outlet by way of a conduit means; said discharge outlet of said compressor is in fluid communication with said condenser inlet of said first coil by way of a conduit means comprising at least one of said flow-controlling devices; said valve outlet of said first coil is in fluid communication with said first coil inlet of said four-way valve by way of a conduit means; said evaporator inlet of said first coil is in fluid communication with said outlet of said first expansion valve by way of a conduit means; said inlet of said first expansion valve is in fluid communication with said first outlet of said second coil by way of a conduit means comprising at least one of said flow-controlling devices; said second outlet of said second coil in fluid communication with said inlet of said second expansion valve by way of a conduit means comprising at least one of said flow-controlling devices; said valve inlet of said second coil in fluid communication with said second coil outlet of said four-way valve by way of a conduit means; said outlet of said second expansion valve in fluid communication with said evaporator inlet of said third coil by way of a conduit means; said valve outlet of said third coil in fluid communication with said third coil inlet of said four-way valve by way of a conduit means; and said compressor inlet of said third coil in fluid communication with said compressor discharge outlet by way of a conduit means comprising at least one of said flow-controlling devices; a first section of duct for conveying air from said product container to said drying enclosure, said first section of duct connected between said exhaust side of said product container and said inlet side of said drying enclosure; a second section of duct for conveying air from said drying enclosure to said product container, said second section of duct connected between said outlet side of said drying enclosure and said intake side of said product container; and at least one blower mounted within one of said sections of duct for forcing air over said product; wherein said product container and said drying enclosure are in fluid communication with one another by way of said sections of duct.
 9. The moisture removal system of claim 8 wherein said switching means comprises a timer.
 10. The moisture removal system of claim 8 wherein said switching means comprises a pressure gauge.
 11. The moisture removal system of claim 8 wherein said switching means comprises a temperature gauge.
 12. The moisture removal system of claim 8 wherein said flow-controlling means are solenoids.
 13. The moisture removal system of claim 8 wherein said flow-controlling means are check valves.
 14. A moisture removal system comprising: a product container for holding a subject product, said product container having an intake side and an exhaust side; a drying enclosure for removing moisture from circulating air, said drying enclosure having an inlet side and an outlet side and comprising a heat pump, which further comprises: a first coil capable of operation as a condenser or evaporator, said first coil having a condenser inlet, an evaporator inlet, and a valve outlet; a second coil capable of operation as a condenser, said second coil having a first outlet, a second outlet, and a valve inlet; a third coil capable of operation as a condenser or evaporator, said third coil having a condenser inlet, an evaporator inlet, and a valve outlet; a compressor with a suction inlet and a discharge outlet; an accumulator with a valve inlet and a compressor outlet; a four-way valve having a first coil inlet, a second coil outlet, a third coil inlet, and an compressor outlet; a first expansion valve having an inlet and an outlet; a second expansion valve having an inlet and an outlet; a plurality of solenoids; and a programmably operable switch in electrical communication with said solenoids for changing the fluid operation of said heat pump to change the respective function of said first and third coil from condenser to evaporator or evaporator to condenser, said switch comprising at least one of: a timer, pressure gauge, or temperature gauge; wherein said suction inlet of said compressor is in fluid communication with said compressor outlet of said accumulator by way of a conduit means; said valve inlet of said accumulator is in fluid communication with said compressor outlet of said four-way valve by way of a conduit means; said discharge outlet of said compressor is in fluid communication with said condenser inlet of said first coil by way of a conduit means comprising one of said solenoids; said valve outlet of said first coil is in fluid communication with said first coil inlet of said four-way valve by way of a conduit means; said evaporator inlet of said first coil is in fluid communication with said outlet of said first expansion valve by way of a conduit means; said inlet of said first expansion valve is in fluid communication with said first outlet of said second coil by way of a conduit means comprising one of said solenoids; said second outlet of said second coil in fluid communication with said inlet of said second expansion valve by way of a conduit means comprising one of said solenoids; said valve inlet of said second coil in fluid communication with said second coil outlet of said four-way valve by way of a conduit means; said outlet of said second expansion valve in fluid communication with said evaporator inlet of said third coil by way of a conduit means; said valve outlet of said third coil in fluid communication with said third coil inlet of said four-way valve by way of a conduit means; and said condenser inlet of said third coil in fluid communication with said compressor discharge outlet by way of a conduit means comprising one of said solenoids; a first section of duct for conveying air from said product container to said drying enclosure, said first section of duct connected between said exhaust side of said product container and said inlet side of said drying enclosure; a second section of duct for conveying air from said drying enclosure to said product container, said second section of duct connected between said outlet side of said drying enclosure and said intake side of said product container; and a blower mounted within one of said sections of duct for forcing air over said product; wherein said product container and said drying enclosure are in fluid communication with one another by way of said sections of duct.
 15. The moisture removal system of claim 13 wherein said programmably operable switch comprises a timer. 